Sheet substrate with surface patterns to facilitate sheet feeding

ABSTRACT

A paperboard sheet and a method of using the paperboard sheet is provided in which a surface of the paperboard sheet provides a pattern of indentations, the indentations reducing the surface area between adjacent sheets to facilitate the transfer of a top sheet from a stack of similar sheets.

RELATED APPLICATIONS

This application claims the benefit of U.S. Application Ser. No.62/720,233 filed on Aug. 21, 2018 and which is incorporated herein byreference.

FIELD OF THE INVENTION

This invention is directed towards a paperboard slip sheet and tiersheet substrate having a plurality of indentations on a least onesubstrate surface, the indentations increasing the surface area of thesubstrate and lowering the coefficient of friction between adjacentsheets in a plurality of stacked sheets and allowing improved air flowbetween adjacent sheets. The lower coefficient of friction allows for aneasier separation of sheets during sheet feeding operations.

BACKGROUND OF THE INVENTION

It is well known in the art to provide stacked sheets of paperboard slipsheets or tier sheets which may be coated or uncoated. As the stackedsheets are individually removed and processed using automated sheetfeeders, the displaced sheet will often adhere to the adjacent stackedsheet. Efforts to prevent the “sticking” of the adjacent sheets haveincluded specialized sheet feeders with preciously placed rollers orusing vacuum systems that are designed to minimize the problem. Otherefforts have included the use of coatings or surface agents applied tothe sheets such as calcium chloride, starch, or other additives that aredesigned to lower the coefficient of friction.

One example of a slip sheet and tier sheet that is known in the art canbe found in reference to U.S. Pat. No. 4,708,247, entitled “Slip Sheet”and which is incorporated herein by reference.

However, there remains room for improvement and variation in the art.

SUMMARY OF THE INVENTION

It is one aspect of at least one of the present embodiments to providefor a method of forming and separating sheets of paperboard, such asslip sheets or tier sheets, within commercial sheet feeding apparatusesand operations.

It is yet another aspect of at least one embodiment of the presentinvention to provide for a paperboard sheet that is adapted forplacement within a sheet feeder and which comprises a paperboardsubstrate having a first surface and a second surface, at least one ofthe first surface or the second surface having a textured pattern formedon the sheet surface, the textured pattern reducing the contact surfacearea between adjacent sheets, the reduced contact surface area being atleast about 10 percent less than untextured sheets.

It is yet another aspect of at least one embodiment of the presentinvention wherein providing a single sheet further includes providing asheet in which both a first surface of the sheet and a second surface ofthe sheet define a pattern for the modified sheet.

It is yet another aspect of at least one embodiment of the presentinvention to provide the textured pattern that reduces the surface areacontact between adjacent flat sheets by at least about 15%.

It is yet another aspect of at least one embodiment of the presentinvention to provide a textured pattern formed on first surface of thesheet and a second surface of the sheet, the pattern being raisedrelative to a first surface of the sheet and being recessed relative tothe second surface of the sheet.

It is yet another aspect of at least one embodiment of the presentinvention to provide a paperboard sheet adapted for use as a slip sheetor tier sheet comprising; a paperboard substrate having a first surface,a second surface, and a thickness of substantially about 0.010 to about0.012 inches; a raised textured pattern formed on an upper surface ofthe sheet, the textured pattern reducing the contacting surface areawith an adjacent sheet in contact with the first surface by at leastabout 10%; a second textured pattern formed on the second surface of thesheet, the second pattern being a recessed pattern formed integral withthe raised pattern wherein when the paperboard sheets are placed in astacked arrangement, the contact area between a first surface of onesheet and a second surface of an adjacent sheet reduces a surface areacontact between the adjacent sheets by at least about 10%.

It is yet another aspect of at least one embodiment of the presentinvention to provide the textured pattern formed on an embossed regionon the paperboard sheet, wherein a width of the embossed line formingthe pattern is about 1/16^(th) of an inch.

These and other features, aspects, and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A fully enabling disclosure of the present invention, including the bestmode thereof to one of ordinary skill in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying drawings.

FIG. 1 is a view of one non-limiting embodiment of a sheet having atextured pattern.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the embodiments of theinvention, one or more examples of which are set forth below. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used on another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncover such modifications and variations as come within the scope of theappended claims and their equivalents. Other objects, features, andaspects of the present invention are disclosed in the following detaileddescription. It is to be understood by one of ordinary skill in the artthat the present discussion is a description of exemplary embodimentsonly and is not intended as limiting the broader aspects of the presentinvention, which broader aspects are embodied in the exemplaryconstructions.

It is to be understood that the ranges mentioned herein include allranges located within the prescribed range. As such, all rangesmentioned herein include all sub-ranges included in the mentionedranges. For instance, a range from 100-200 also includes ranges from110-150, 170-190, and 153-162. Further, all limits mentioned hereininclude all other limits included in the mentioned limits. For instance,a limit of up to 7 also includes a limit of up to 5, up to 3, and up to4.5.

As used herein, the term “substantially about” is given a meaning ofplus or minus 10 percent of the stated value unless otherwise indicated.

In describing the various FIGURES herein, the same reference numbers areused throughout to describe the same material, apparatus, or processpathway. To avoid redundancy, detailed descriptions of much of theapparatus once described in relation to a FIGURE is not repeated in thedescriptions of subsequent FIGURES, although such apparatus or processis labeled with the same reference numbers.

As seen in reference to FIG. 1, a paperboard sheet 10 is provided whichmay be used as a slip sheet or tier sheet. Sheet 10 can be formed from asingle or multiple ply arrangement and may include up to 100% recycledfiber chip board. Sheet 10 can also be coated or uncoated. In onepreferred embodiment, the upper sheet surface 11 has a raised embossedpattern 12 seen here as a repeating pattern of squares applied in asubstantially diagonal pattern to the surface 11. A correspondingdebossed pattern of depressions is formed on the lower surface of sheet12 the depression pattern being integral to the raised pattern 12 of thetop surface. When stacked, the placement of the debossed lower surfaceof a top sheet onto a similar pattern of an embossed raised surface ofthe adjacent, provides a region of reduced contact between the adjacentstacked sheets compared to two opposing smooth sheet surfaces.

As seen in FIG. 1, a pattern 12 of a textured surface is formed on atleast one surface of sheet 10. The pattern 12 can be created on thesheet surface using a variety of techniques including embossing rollers,die cutters, platen presses, or cutting/scoring tools.

The pattern 12 increases the surface area of the treated surface of thepaperboard sheet 10. By increasing the surface area of the sheet, theamount of surface area contact with respect to the pattern 12 to anadjacent sheet surface is correspondingly decreased. The decrease in theamount of contact surfaces lowers the coefficient of friction betweenadjacent sheets and allows the mechanical separation of a stacked supplyof sheets using a vacuum separation or a sheet feeder, to beaccomplished more easily and with less jamming or feeding of multiplesheets. The pattern also provides a space between sheets that allows airflow between the sheets to facilitate sheet separation, particularlywhen using vacuum separation technology.

Preferably, it is desirable to provide a surface pattern 12 in which thecontact surface of the pattern 12 with an adjacent sheet is lowered byat least about 10% and more preferably between 15% to about 50%. Thelowering of the percentage of contact surfaces between adjacent sheetsallows the separation of stacked sheets to be done more easily and withfewer instances of non-separation of sheets.

In some embodiments, the pattern 12 can be comprised of a raised patternon only one surface. In other embodiments, the pattern 12 involvesmodifying the sheets surface such that only depressions are formed belowthe initial sheet surface. The pattern can include lines, overlappinglines, stippling, embossed logo patterns, and other geometric or randompatterns. Ideally, the surface area contact between the adjacent sheetsis reduced by at least about 15% in order to improve sheet separationand may include sheets having a raised pattern on one surface to arecessed pattern on a lower surface.

In accordance with the invention, it has been found useful for theembossed pattern to still allow for the flat stacking of sheets. As ageneral rule, it is undesirable to create an uneven height differenceson a portion of a sheet that results in a shingling of stacked sheets.

In accordance with this invention, it has been found that not allportions of a sheet need to be subjected to the pattern forming process.For instance, a pattern can be applied to just a boundary edge margin ofa sheet, localized to a center portion of a sheet, be in the form of aseries of parallel strips, a large X pattern, or other configurationssuch that selected portions of the sheet surface are modified so as tobring about the desired reduction in the surface area contact betweenthe sheets and thus result in a lower coefficient of friction betweenthe sheets.

For instance, the pattern 12 seen in FIG. 1 could be squares or adiamond shaped chevron type pattern in which each individual square orother polygon shape has an interior surface area of between about 3.6 toabout 4.2 square inches.

The depth/height of the score lines for embossing or debossing can bevaried, For instance, a 1/16 of an inch raised/depth dimension has beenfound to work well with slip sheets having a thickness of between about0.025 inches to about 0.050 inches. It has further been found that usinga 1/16 inch width profile to the score or embossed regions hassufficient dimensions with respect to the paper texture such thatadjacent sheets will not register or nest within similar overlappingpatterns. By not forming a tight nested pattern, the ease of separationis facilitated when a top sheet is separated from a lower adjacentsheet.

Although preferred embodiments of the invention have been describedusing specific terms, devices, and methods, such description is forillustrative purposes only. The words used are words of descriptionrather than of limitation. It is to be understood that changes andvariations may be made by those of ordinary skill in the art withoutdeparting from the spirit or the scope of the present invention. Inaddition, it should be understood that aspects of the variousembodiments may be interchanged, both in whole, or in part. Therefore,the spirit and scope of the invention should not be limited to thedescription of the preferred versions contained therein.

What is claimed:
 1. A process of improving the separation of a singlesheet in a stack of a plurality of similar sheets comprising: providinga single sheet, a first surface of the sheet defining a pattern oftextured surface features, there by providing modified sheet; stacking aplurality of the modified sheets; displacing a single sheet from theplurality of stacked sheets, the single sheet having a lower coefficientof friction with an adjacent sheet, thereby lessening the separationforce needed for sheet separation.
 2. A paperboard sheet adapted forplacement within a stack supply of similar sheets in a sheet feedercomprising: a paperboard substrate having a first surface and a secondsurface; a textured pattern formed on at least the first surface of thesheet, the textured pattern reducing the surface area contact within anadjacent flat sheet by at least about 10%.
 3. The process according toclaim 1 wherein step of providing a single sheet further includesproviding a sheet in which both a first surface of the sheet and asecond surface of the sheet define a pattern for the modified sheet. 4.The paperboard sheet according to claim 2 wherein the textured patternreduces the surface area contact between adjacent flat sheets by atleast about 15%.
 5. The paperboard sheet according to claim 2 whereinthe textured pattern is formed on first surface of the sheet and asecond surface of the sheet, the pattern being raised relative to afirst surface of the sheet and being recessed relative to the secondsurface of the sheet.
 6. A paperboard sheet adapted for use as a slipsheet or tier sheet comprising: a paperboard substrate having a firstsurface, a second surface, and a thickness of substantially about 0.010inches; a raised textured pattern formed on an upper surface of thesheet, the textured pattern reducing the contacting surface area with anadjacent sheet in contact with the first surface by at least about 10%;a second textured pattern formed on the second surface of the sheet, thesecond pattern being a recessed pattern formed integral with the raisedpattern wherein when the paperboard sheets are placed in a stackedarrangement, the contact area between a first surface of one sheet and asecond surface of an adjacent sheet reduces a surface area contactbetween the adjacent sheets by at least about 10%.
 7. The paperboardsheet according to claim 6 wherein the textured pattern is formed froman embossed region on the paperboard sheet, and a width of the embossedline forming the pattern is about 1/16^(th) of an inch.